Dam.



N. L. HALL.

DAM.

APPLoATIoN FILED JANl 2, 1908.

Patented June 8, 1909.

A I ar,

MAM(

UNITED STATES PATENT oEEIoE. l

NEWTON L. HALL, OF SAN DIEGO, CALIFORNIA.

DAM. l

Specification of Letters Patent.

Patented June 8, 1909.

Application filed January 2, 1908. Serial No. 409,092.

,To all whom it may concern:

13e it known that I; NEWTON L. HALL, a citizen of the United States, residing at San Dpi-gol,i f1n the county of San Diego andState o a sealing of the dam beine effected by a Wall `wall where defective.

of relatively small massiut of impermeable structure, vextending throughout the dam `from end to end. In these dams, known as fill dams, the .impermeable wall may be either a core wall in the interior of the dam, or a lining, generally at the upstream face of the dam. 1

The present invention is directed particularly to the construction of such a' wall, whether used as a core Wall or as a lining, and the main object of the invention is to enable the condition of the wall as to leakage to be readily ascertained at any time, and if defects occur, to enable repair of the In this connection, vthe invention provides also for the inspection and repair of the rock bed,- and for detecting and remedying a condition of leakage under the dam.

A further object of the invention is to provide a wall for the above stated purpose, of maximum strength and stability for a given amount of material used.

In the accom anying drawings: Figure ,1 is a longitudina vertical section of a dam,

'dam showingthe application of the invenv tion to' the lining of a vrock fill dam.

Referring to Figs. '1 to 3, thedam comprises a iillv ortion 1` of loose rock or earth, sloping on oth upstream land downstream faces, and a heart wall or core wall 2, extending vertically within the dam directl below the crest of the dam, said core wa bein built up directly from the rock bed or subase 3. 'The core wall 2 is. hollow or formed with an interior chamber or open space 4, and the two side walls 5 of said core wall referabl diverge downwardly so that thisy c amber 1s wider at the bottom than at the top. The walls 5 of the core may also ornia, have invented a new and useful Dam, of which the following is a specifi-` be wider at the bottom than at the top, the core wall thus having steeply sloping up and downstream faces. Walls 5 are separate at the bottom, leaving the sub-base exposed.

To brace the structure and withstand the inward pressure on these walls, spreaders 6 are formed between the walls, extending from wall to Wall, said s readers bein preferably arched.- The ho low core wa l, including the spreaders, is preferably formed of cement or concrete so as to form an interal mass, the concrete being preferably reirl-forced. The term cement 1s herein used to include all such integral molded cement construction. At its upper end this core wall may have a solid portion, indicated at 8.

To permit access to the interior of the liollow core Wall, an entry passa e 10 is 'formed in the rock at the side of the am, this entry passage opening at one end at'a convenient point for access, and opening at the other end into the interior chamber 4 in the core wall. The space between the spreaders in said chamber is of sufficient size to permit of the passage of a man in suoli space, and thus enable inspection of every part of the inner face of each wall of the core, as well as inis exposed at the bottom of the core chamber.

To continually drain away any leakage that may occur, a drainage pipe 12 is provided extending rom the lower end of the gore chamber to the downstream face of the If at any time it appears from inspection of the inner faces ofthe walls of the core 2, particularly the upstream wall, thata leakage' is taking place, the defect can be remedied by filling that portion of the core solid from wall to wall with cement or concrete. By goin to the bottom of the interior chamber of t e core wall, the ins ector can ex amine the section or strip of t e rock bed extending the entire length of the dam, from one side of the rock bed to the other, so that if there is seepage under the rock bed orsubbase below the d'am'at any point, it can b`e detected and can be remedied by grouting out the rock thereat and filling in with cement.

The hollow structure of the core wall has the advantage that it gives a greater transverse dimension and, therefore, a greater stability for a given weight of material as compared with a solid wall, and this increase of stability is augmented by the eliect of the spection ofthe rock bed or sub-base where it lining solid, and also to enable leakage in the slope of the core wall. hollow beam, braced by spreaders 6, 'and is stiffer and stronger than a solid core of the same wei ht. This is of special value with an arche dam. The pressure of the rock iill, or of the Water, as the case may be, in contact with each face of wall 1, being normal to the sloping face of the core wall, such pressure has a component directed downwardly tending to hold the core Wall in position at the base and to bring the line of pressure within the base, thereby increasing the stability, both as regards longitudinal dislacem'ent and overturning.- This self-bracing of the core also enables the reinforcement to be'reduced to a minimum.

In applying the invention to the lining of `a rock iilled dam, as shown in Fig. 4, the lining 13 is formed with an interior chamber 14, with spreaders 15, extending across from the upstream wall 16 to the-downstream wall 17, and said lining will conform in a general Way to the shape of that facefof the dam, and may be applied to either or both faces of the dam. Thus, with the form of dam shown, the lower portion of the lining is vertical and the upper portion slopes to rest on the upstream face of the upper portion of the rock fill 18 'of the dam. A drain pipe 19 leads from chamber 14 of the lining, under the rock iill, to the lower end of the dam, to discharge any water leaking into said chamber. The interior of this hollow lining is reached from the outside by a passage, as shown in Fig. .1, enabling inspection of the interior chamber 14 of the lining so as to enable any leakage in theiwall thereof to be detected and remedied by, making that portion of the sub-base to be detectedanc1 remedied, as in case ofthe core wall, the upstream and downstream walls of the lining being sufficiently separated to expose a strip of the rock bed or sub-base the entire length of the dam.

The hollow construction of the linin has the sameadvantages as above set fort for the hollow construction of the core wall, with the addition that the greater stiffness of the 'lining for a given weight enables it to meet the special strains brought thereon due to settling. In any case the seal wall 2 or 13 is of insufficient width, relatively to its height, to present the moment of stability required for withstanding the pressure of the water on the upstream-face, the wei ht of the rock fill being relied on to prevent, y its lateral pressure, the overturning of the dam.

A further advantage of the hollow construction of the wall, particularly incase of the lining wall, is that it is adapted to withstand the effects of changes of temperature, the hollow wall. or interior space serving as a heat insulation between the outer and inner faces so that the crackingstrains due to rapid The wall acts as a change of temperature,betweentheinnerand outer faces of a solid wall, are obviated. With a hollow wall, moreover, any crack that forms in one wall will not extend or spread to the other wall of the core.

'Ihe essential feature of the invention resides in means for providing a wall of sufficient thickness to act as a seal but not to present the required weight and base for stabil ity, and supporting the wall against the pressure ofthe water by a rock fill in such manner that a space is left between the wall and the rock fill, for inspection of the wall and for repair at points of leakage. For this purpose the invention com rises in addition to the seal wall, namely, t e upstream wall 5 or 13, and the rock fill 1 or 18, a supporting or back Wall, namely, the Wall 5 or 13 on the downstream side of the seal wall, to receive the pressure of the rock fill and transmit it to the` seal wall, this back Wall bein separated from the seal wall and connecte thereto by the spreaders 6 o1' 15 so as to transmit the lateral pressure ofthe rock fill to the seal wall.

What I 'claim is 1. Ina dam, a seal wall, theproportion of the width of said wall to its height presenting insufficient moment of stabilityv to prevent overturning of the wall by the pressure of water exerted against its upstream face, said seal wall being formed with upstream and downstream portions separated to allow access to the back of the seal wall, a rock fill on downstream side of the Wall and exerting pressure against the downstream face of the lwall, and spreaders transmitting the lateral pressure of the rock fill from the downstream to the upstream portion ofthe wall.

2. In a dam, a seal wall built on the rock bed of the dam, the proportion of the width of said wall to its height presenting insuilicient moment of stability to prevent ovcrturnin of the wall by the pressure of water exerte against its upstream face, said seal wall being `formed with u stream and down stream portions separate to allow access to the back of the upstream portion of the seal wall and to the rock bed at the bottom of thedam, a rock fill on downstream side of the wall and exerting pressure against the downstream face of the wall, and spreaders transf4 y NEWTON L. HALL.

In presence of GEORGE T. HACKLEY, FRANK L. A. GRAHAM.: 

